Really, if the truth were
known, this was the very first compound used
as an “ancillary” medication by steroid-using athletes. Dan Duchaine
had first speculated that it could possibly be used by bodybuilders to
halt the development of gynocomastia (breast tissue in males), because
it was used to stop breast tumors in women. He was, as usual, correct.
Since then, Nolvadex has become the most widely used medication in the
world for men on a steroids looking to avoid gyno.
Nolvadex is a SERM or
Selective Estrogen Receptor Modulator
. The “selective”
part means that it acts as an estrogen agonist in some tissues and as
an estrogen antagonist in others. The “Estrogen Receptor Modulator”
part means that it acts on the Estrogen Receptor (called the "ER" but
having nothing to do with George Clooney or Anthony Edwards).
The estrogen receptor's ligand binding domain is just of a number of
amino acid sequences "folded" into a series of helixes, which have the
ability to change conformation. Different stimuli (such as Nolvadex
) are well
documented to have the ability to change the conformation of a very
important helix (helix 12, for those keeping score at home).
When estradiol binds the ER, this particular helix takes on a
conformation that allows DNA transcription to mRNA, and estrogenic
effects are then expressed in the body. When Nolvadex (Tamoxifen)
binds to it, the antagonist changes the shape of this helix in such a
way that it now folds (or bends) in such a way to prevent proper
binding of estrogen, and subsequent transcription of DNA to mRNA.
The ER (remember, no George Clooney, no Anthony Edwards) contains two
areas called AF-1 and AF-2. Nolvadex actually only inactivates AF-2.
Since there are two areas that can can initiate transcription of mRNA,
and Nolvadex is estrogenic in some tissues but an anti-estrogen (sort
of) in others,it is possible that AF-1 is the dominant domain of
estrogen gene transcription in the liver (for example) but not in
mammary (breast) tissue. Thus, Nolvadex
exerts different effects as regards estrogen, in different tissues
Hence, we can see that the effect of Nolvadex is via the mechanism of
estrogen receptor blockade of breast tissue 
Contrary to popular
opinion, total body estradiol actually increases with use of Nolvadex.
It is not, as it’s often called an “Anti-Estrogen.”
Fig 1. Tamoxifen Anti-Estrogenic
Some other positive effects of Nolvadex (acting this time as an
estrogen agonist) is that it can be beneficial to a properly
functioning immune system as well as your lipid profile (cholesterol)
should also show marked improvement with administration of tamoxifen
It’s actually very useful stuff during a cycle for immune, joint, and
Nolvadex also has some highly important and practical roles for a
steroid using athlete who is coming off a cycle. Hypogonadic and infertile men
given Nolvadex, saw significant increases in the serum levels of LH,
FSH, as well as testosterone levels 
. In fact, 20mgs
of Nolvadex can possibly raise your testosterone levels
clearly this is something we should consider using not
only during a cycle to prevent gyno, but especially afterwards, to
restore our natural hormonal function.
Unfortunately, it has been linked to reduced gains in some
bodybuilders. This is as a possible result of Nolvadex’s potential to
possibly reduce IGF
levels, which are important for muscle growth. Additionally, some
people report vision problems with its use, but I didn’t find that to
be the case for me.
Still, for PCT,
or even on a cycle, most people find Nolvadex to be an indispensable